What is the brief instructions on investing?
Can a normal person like myself invest on stock markets and how is it done, is it possible that I will gain a lot of money?
Can you pull your stocks out at anytime and keep the money that you've earned?
How can you become a good investor and what is the minimum limit you can put on a stock market?

Yes anyone can play the stock market. All you need is an account with a brokerage house to make your trades for you. You can't enter trades directly.

It is certainly possible you will gain lots of money, its also possible you will lose your shirt. You can sell your holdings whenever you want and take the cash (assuming your stocks have gone up in value).

There have been dozens of whole books written on how to play the stock market so there is no way anyone could go into the whole thing here. I suggest checking out your library, local bookstore or amazon.com for such books.

An online broker like Scottrade is the best way to start. I use Scottrade and I am very happy with the quick execution. The markets now are very volitile and tricky. If you must start now, be very prudent. Study the companies you wish to invest in and even call them.
Another way to invest would be the direct investment program. Many companies, good companies, have such a program. You not only bypass brokerage fees, but you may buy small amounts of stock over a long period, thereby building up a valued portfolio.

As for books on the subject, I swear by How To Make The Stock Market Make Money For You. By Ted Warren. It is older and the charts are older but it teaches you to watch the insiders and how they accumulate many shares without making big moves. When they have the amount they want, they make the moves that draw in the public then whip saw the public. If you are in on that secret and know how to recognize it, you can win. Good Luck.